The present invention relates to a position detection system and an interactive board employing the position detection system.
In interactive boards employing conventional position detection systems, ultrasonic waves transmitted by a stylus making contact with a board (coordinate data input plane) are generally reflected by one or more reflecting plates (located, for example, on upper right and left sides of such a vertical interactive board) and the reflected ultrasonic waves are received by one or more ultrasonic wave sensors, and the position of the stylus is detected based on the received ultrasonic wave signals. For example, U.S. Pat. Nos. 6,100,877; 6,104,387; and 6,147,681 are referred to. Images displayed on the screen of a personal computer are projected by a projector onto the coordinate data input plane of such an interactive board, and instructions to the display screen of the personal computer are given by use of the stylus, thereby switching of images displayed on the display screen of the personal computer, touch-up or correction of displayed images, etc. are made possible.
The primary object of the present invention is to provide a position detection system capable of receiving signals (ultrasonic wave signals etc.) transmitted by transmitter means such as stylus movable on the coordinate data input plane and thereby conducting the position data input or position detection with high precision.
In accordance with one aspect of the present invention, there is provided a position detection system comprising: movable transmitter means for generating to transmit an electromagnetic wave and an ultrasonic wave; first detection means for detecting the electromagnetic wave from the transmitter means; second detection means for detecting the ultrasonic wave from the transmitter means; and position detection means for detecting the position of the transmitter means based on the result of the detection by the first detection means and the second detection means. The second detection means has an opening through which the ultrasonic wave passes so as to be detected thereafter. The opening is formed so that the ultrasonic wave passing through the opening will propagate radially from the center of the opening.